We have a water tank that's just 6.5 - 7 ft above ground level. The length of the pipe from water tank to sink tap would be around 25 ft. Output from water tank is an 1.5 inch pipe which then reduced to 1 inch pipe after 5 ft. Then the remaining 20 ft (1 inch pipe) is connected to sink tap which then finally reduced to 0.5 inch as per sink tap size. Sink tap is 3 ft above ground level. Due to the lower tank height and thus lesser gravitational pressure (???), the flow rate (also pressure ?) in the sink tap is not optimal (or I could say it's bit below usual flow rate). So plumber is considering following strategies to increase the flow rate (pressure ?) at the sink tap.
Increase the tank height further 3 ft (10 ft above ground level)
Starting 10 ft length would be covered by 1.5 inch pipe
Reduce from 1.5 inch to 1.25 inch after 10 ft
Next 10 ft length would be covered by 1.25 inch pipe
Reduce from 1.25 inch to 1 inch after that
Remaining 5 ft length would be covered by 1 inch pipe
Finally the 1 inch pipe is reduced to 0.5 inch at the sink tap connection
Obviously increasing the tank height would increase the flow rate (due to increased pressure), but does gradually reducing the pipe size (3 times) along the way increases the flow rate (pressure ?) at the end (sink tap) than what it was before?